Support for trencher tooth



Dec. 28, 1965 J. G. BENETTI 3,225,468

SUPPORT FOR TRENGHER TOOTH INVENTOR. E I JOHN BEA/E TT! ATTORNEY United States Patent 3,225,468 SUPPORT FOR TRENCHER TOOTH John G. Benetti, Cnpertino, Calif, assignor, by direct and mesne assignments, of one-half to Geraid A. Petersen, Santa Clara, Calif., and one-half to Anita E. Petersen, Saratoga, Calif.

Original application Dec. 4, 1961, Ser. No. 156,907, new Patent No. 3,152,142. Divided and this application Nov. 5, 1963, Ser. No. 321,557

Claims. (Cl. 37191) This invention relates to new and improved support for trencher tooth. More particularly, the invention relates to a means for attachment of a tooth holder to the chain of a chain-type trenching machine. This application is a division of co-pending application Serial No. 156,907, filed December 4, 1961, now Patent No. 3,152,142.

A common type trenching machine comprises a boom which serves as a guide for a continuous chain of the roller type, the chain being provided at intervals with teeth carried thereby. In accordance with the present invention, the teeth are replaceable and hence are received and retained in holders, which holders are connected to the chain by supports. In a common chain-type trenching machine the teeth are arranged in series whereby the first tooth in the series is centrally located, subsequent teeth are laterally outwardly slanted and the last teeth in the series are arranged in .pairs in dual holders whereby one tooth of each pair is disposed on each side of the chain. The advantage of the above-described arrangement of the teeth is that the cut begins at the center in a width equal to the width of one tooth and then widens out as the chain progresses, thereby facilitating the digging operation. It is a feature and advantage of the present invention that the tooth holding means for all of the foregoing lateral spacings of teeth may be supported by the chain in substantially the same manner.

The principal feature of the present invention is the fact that the holder divides the strain imposed on the chain by the digging action on two links rather than on a single link. The back pressure on the tooth holder is absorbed partially by an upward lift on the link of the chain to which the holder is primarily attached and a downward pressure on a link to the rear thereof.

Among the advantages of the foregoing arrangement is the fact that the pressure is applied at two points rather than at a single point, and hence the strain tending to wear or break the chain is correspondingly reduced.

A still further feature of the invention is the fact that the tooth is held more securely and is retained more securely in proper digging position.

A still further advantage of the invention is the fact that the foregoing features contribute to a longer life of the chain, easier operation of the trenching machine and a more rapid digging action.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

FIG. 1 is an end elevation of a portion of the chain of a trenching machine, partly broken away in section.

FIG. 2 is a side elevation of the structure of FIG. 1.

FIG. 3 is a bottom plan of the structure of FIG. 1.

FIG. 4 is a fragmentary sectional view taken substantially along the line 44 of FIG. 2.

FIG. 5 is an exploded view, showing the structure of FIG. 4 prior to assembly of the tooth in its holder.

The chain 11d with which the present invention is used may be of the conventional roller type. Such a chain has short longitudinally extending outer links and inner links 13d arranged in pairs on opposite sides thereof. Each inner link 13d is disposed inwardly and the next outer link partially overlaps the inner link and is parallel thereto. Positioned between the inner links 13d and spacing the same apart are rollers 14d. Pins 16d with enlarged heads extend through the outer links, through the inner links 13d and through the rollers 14d, thereby passing from side to side of chain 11d. At spaced intervals along the length of chain 11 are connecting links or supports 71.

Support 71, which is the subject of the present invention, has at its outer end a tooth holder 22d holding replaceable tooth 23d. In end elevation (-FIG. 1) support 71 is substantially U-shaped. The legs 73 of the holder are spaced apart about the same distance as the inner links 13d of chain 11d and diverge slightly inwardly and are formed with apertures to receive pins 16d. The toothholding means located on web 72 shown herein resembles that illustrated in Patent No. 2,968,880. This portion of the tooth-holder may be defined as essentially H-shaped in the sense that it is formed with a vertical web 32 extending between transverse member 33 which comprises a thickening and reinforcement of web 72 and spaced transverse member 34. Thus, a recess for the tooth is provided having walls 37, 38 at the bottom and top, respectively (as viewed in the Working position of the tooth in FIGS. 1 and 2) which are parallel and having transverse walls 39 on either side of web 32. The recess receives tooth 23d as hereinafter set forth. Extending transversely horizontally through web 32 is a hole 41 which receives a resilient insert 42 formed of rubber, neoprene, or the like, and which is preferably circular in cross-section. The length of insert 42 is substantially greater than the width of web 32. In order to allow the insert to bend backwardly, grooves 43 are formed in walls 39 rearwardly of hole 41, grooves 43 being preferably semicircular in cross-section and having a radius approximately equal to the radius of insert 42. It will be observed that at the rearward end of holder 22d there are rearward facing openings 44 on either side which provide access to the recess. A tool may be inserted into opening 44 and used to force tooth 23d forwardly and out of holder 71 against the restraining power of resilient insert 42 which tends to retain the tooth in the holder.

The tooth 23d which is herein illustrated is also similar to that shown in Patent No. 2,968,880. Essentially, it consists of tapered distal faces 46 having cutting edges 47 which are reversible in the sense that the tapered top and bottom distal faces 46 are truncated at the front edge. Rearwardly of top and bottom faces 46 are proximal prongs 48 or roots on either side of the tooth separated from each other by a rectangular slot 49 which extends forwardly from the proximal end of the tooth. The width of slot 49 is approximately equal to the distance between walls 39. Vertical side walls 51 are formed defining the sides of slot 49 and it is against these walls that resilient insert 42 presses to hold the tooth in its holder. The spacing between walls 37, 38 of holders 22d accommodates the thickness of prongs 48. To assist in holding tooth 23d in alignment relative to holder 22, a notch 52 may be formed forwardly of slot 49 having a width equal to approximately one-half the width of slot 49. Correspondingly, web 32 is formed with a reduced width portion 53 forwardly of hole 41, which reduced width portion 53, fits into notch 52. The foregoing construction prevents the strains imposed on the tooth from skewing the tooth out of proper alignment.

Notches 54 may be formed extending transversely across top and bottom surfaces of prongs 48. Reference is made to Patents No. 2,877,574 and No. 2,952,085 for means for securing teeth thus constructed to a holder by means other than those illustrated herein.

Tooth support 71 is preferably directly connected into chain 11d rather than being attached to connecting links in the chain. This modification is most conveniently used with that type roller chain wherein the connecting pins 160! between links are detachably inserted rather than being rivetted or otherwise permanently secured in place. Support 71 comprises a horizontal table 72 which is generally parallel to but spaced from chain 11d, and has legs 73 projecting therefrom which are spaced apart the same distance as outside links 12d. Table 72 is generally rectangular in plan having slightly outwardly flared rear edges 75. Legs '73 are apertured to receive pins 16d in the same manner as links 12d in the chain.

Extending transversely on the underside of table 72 one link rearwardly is a boss 74 having a central concave pad 76 which bears against roller 14d one length to the rear of the rearmost pin 16d connecting legs 73 to the chain.

Table 72 carries one or more tooth holders 22d supported on stems 77. In the accompanying drawing two holders 22d supported by stems 77 on opposite sides of table 72 are shown, this being a preferred arrangement. Gussets 78 support the outside edges of table 72 from legs 73.

It will be seen that force 55d applied to tooth 23a is distributed over at least two links in the chain. Thus, the force 55d imposes a lifting force on legs 73 and an inward pressure transmitted by pad 76 against the roller 14d with which it is in contact.

Although the foregoing invention has been described in some detail, by way of illustration and example for purposes of clarity of understanding it is understood that certain changes and modifications may be practiced within the spirit of the invention and scope of the appended claims.

What is claimed is:

1. For use with a trenching machine, the combination comprising an endless chain having a plurality of pairs of first links, a plurality of pairs of second links displaced outwardly and also longitudinally of some of said first links, adjacent links overlapping, at least one tooth support having legs parallel to said links and spaced apart the same distance as pairs of second links, displaced outwardly and also longitudinally of other of said first links and overlapping adjacent first links, transverse rollers between opposite ends of said first links, each said roller having a diameter less than the width of said first links in a direction transverse to the length of said chain, first pins each passing through overlapped ends of a pair of second links and of a pair of first links and a roller, second pins each passing through overlapped ends of a pair of legs and of a pair of first links and a roller, said tooth support having a table interconnecting the outer ends of said legs, tooth receiving means on said table shaped and positioned to receive a portion of a forward pointing tooth, said legs of a single tooth support being connected to two consecutive second pins, said table having a rearward extension formed with a pad shaped to engage a roller rearward of said two consecutive second pins, said pad engaging said roller for substantially the entire length of said roller and being confined laterally of said chain by portions of said first links to either end of said roller,

whereby stress imposed by a tooth on said tooth receiving means is distributed to said two consecutive second pins,

said last mentioned roller and to the first pins passing through said last mentioned roller, and to all the links through which said last mentioned three pins pass.

2. The combination of claim 1, which further comprises second tooth receiving means on said table, said first mentioned and said second tooth receiving means positioned on opposite sides of said chain.

3. The combination of claim 2, in which said table extends laterally to either side of said chain and which further comprises gussets supporting the outside edges of said table from said legs.

4. For use with a trenching machine, an endless chain having pairs of links with overlapping ends on opposite sides of the chain, transverse rollers between ends of pairs of links, each of said rollers having a diameter less than the width of said links in a direction transverse to the length of said chain, first pins through said rollers and said overlapped ends, a tooth support having legs parallel to said links, an end of each leg overlapping an end of a link of said chain, second pins through each end of said leg and said last mentioned ends and one said roller, said tooth support having a table interconnecting the outer ends of said legs, tooth receiving means on said table shaped and positioned to receive a portion of a forward pointing tooth, said table having a rearward extension formed with a pad disposed centrally of said chain and shaped to engage a roller rearward of said legs, said pad engaging said roller for substantially the entire length of said roller and being confined laterally of said chain by portions of said links at either end of said roller.

5. A tooth support having parallel legs with aligned holes at opposite ends of inner edges of said legs, said legs spaced apart with a longitudinal space between said legs, a table interconnecting the outer edges of said legs, toothreceiving means on said table shaped and positioned to receive a portion of a forward pointing tooth, said table having a rearward extension formed with a pad disposed centrally relative to the space between said legs, said pad having an extended length transversely of said support, the ends of said pad located adjacent but spaced from reference planes, each including an opposed surface of said legs, the inner edge of said pad being arcuate in end elevation with a center of curvature lying on a reference line which is an extension of a line connecting the centers of said holes and is spaced from the center of the rearmost of said holes a distance equal to the distance between the centers of said holes.

References Cited by the Examiner UNITED STATES PATENTS 2,389,936 11/1945 Rupp 299-82 2,498,788 2/ 1950 Bremer 74-250 2,666,273 l/ 1954 McIninch 37l91 2,844,042 7/ 1958 Mercier 74245 3,049,824 8/ 1962 McIninch 37191 3,152,412 10/1964 Benetti 37l91 FOREIGN PATENTS 144,711 2/ 1936 Austria. 592,671 2/ 1934 Germany.

CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3, 225,468 December 28, 1965 John G. Benetti It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the heading to the printed specification, line 8, and column 1, line 16, for "Patent No 3,152,142", each occurrence, read Patent No. 3,152,412

Signed and sealed this 6th day of December 1966.

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Offioer Commissioner of Patents 

5. A TOOTH SUPPORT HAVING PARALLEL LEGS WITH ALIGNED HOLES AT OPPOSITE ENDS OF INNER EDGES OF SAID LEGS, SAID LEGS SPACED APART WITH A LONGITUDINAL SPACE BETWEEN SAID LEGS, A TABLE INTERCONNECTING THE OUTER EDGES OF SAID LEGS, TOOTHRECEIVING MEANS ON SAID TABLE SHAPED AND POSITIONED TO RECEIVE A PORTION OF A FORWARD POINTING TOOTH, SAID TABLE HAVING A REARWARD EXTENSION FORMED WITH A PAD DISPOSED CENTRALLY RELATIVE TO THE SPACE BETWEN SAID LEGS, SAID PAD HAVING AN EXTENDED LENGTH TRANSVERSELY OF SAID SUPPORT, THE ENDS OF SID PAD LOCATED ADJACENT BUT SPACED FROM REFERENCE PLANES, EACH INCLUDING AN OPPOSED SURFACE OF SAID LEGS, THE INNER EDGE OF SAID PAD BEING ARCUATE IN END ELEVATION WITH A CENTER OF CURVATURE BLYING ON A REFERENCE LINE WHICH IS AN EXTENSION OF A LINE CONNECTING THE CENTERS OF SAID HOLES AND IS SPACED FROM THE CENTER OF THE REARMOST OF SAID HOLES A DISTANCE EQUAL TO THE DISTANCE BETWEEN THE CENTERS OF SAID HOLES. 